The present invention relates to a digital camera capable of executing a strobe photographing, and particularly to such a digital camera having a white balance adjusting function.
In digital cameras, a color of a captured object may appear different from an original color of the object depending on a type of a light source. For example, a color of a white object photographed under the sun light is different from a color of the object under fluorescent lamp light. Generally, the latter is slightly greener than the former.
In order to avoid the color difference due to a difference of the light source type, a digital camera is typically provided with a white balance sensor. With the white balance sensor, a color of the object, i.e., a color temperature of the object is measured, and corresponding to the thus measured color temperature, the color image signal obtained from an image capturing element is processed to adjust the color of the image so that a white object can be captured as a white image. An example of such technique is disclosed in Japanese Patent Provisional Publication No. P2004-193715A, which discloses a digital camera provided with the white balance sensor. Depending on whether a strobe emits light or not, the white balance is adjusted so that the image of the object shows the object with appropriate colors.
When an object such as people or stationary objects are located relatively close indoors or there is a night lighting environment with the digital camera, the strobe device is generally used to illuminate the object. A Xenon illumination has a color temperature of 5400 K. Therefore, the digital camera having the white balancing function is configured to meet the color temperature when the strobe device (i.e., Xenon lamp) is used. With this configuration, even if the strobe device is used, the object is photographed such that the captured image represents the actual color. However, for objects which are not sufficiently illuminated by the strobe light but mainly illuminated with other lighting devices such as a fluorescent light (whose color temperature is 4200 K) or a filament lamp (whose color temperature is 3000 K), the captured image does not represent the actual colors thereof since the white balance is not adjusted. Such objects are captured such that the color represented by the image is greenish or reddish.
FIG. 7A shows a composition when a person close to the digital camera is photographed using the strobe illumination. Since the person in the composition is illuminated with the strobe light, the color temperature is 5400 K, while a background (i.e., a dotted area) is being illuminated with the filament lamp, and the color temperature at the area is 3000 K. If the white balance is adjusted to meet the strobe illumination, the background is photographed as a reddish image.